The term you may be thinking of is intensive pronoun, which is a pronoun that adds emphasis to a noun or pronoun. They are formed by adding "-self" or "-selves" to a personal pronoun.
Here are some examples:
* I myself will go.
* You yourself can do it.
* They themselves decided to leave.
In these examples, "myself," "yourself," and "themselves" are intensive pronouns that add emphasis to the subject ("I," "you," "they").
Intensive pronouns are often confused with reflexive pronouns, which also use "-self" or "-selves" but have a different function. Reflexive pronouns refer back to the subject of the sentence and are necessary for the sentence to be grammatically correct.
For example:
* I hurt myself. (Reflexive pronoun)
* I myself hurt him. (Intensive pronoun)
In the first sentence, "myself" is a reflexive pronoun because it refers back to "I." In the second sentence, "myself" is an intensive pronoun because it emphasizes "I" without changing the meaning of the sentence.